Fixing a SD->MH conversion

A friend (who isn't yet a listie but will be RSN) just picked up a SD->MH
conversion...

FOR FREE!!! (Lucky SOB...)

Of course its a fixer-upper but then again a complete wg6101 is nothing
to sneeze at. Maybe he'll pick up the dedicated MH that was butchered
into a trivia machine (sob, sniff) and cobble the two together.

Anyways, the monitor is dirty & rusty as hell but complete with no signs
of major damage aside from the TO-3s on the upright left side hanging
loose.

Sadly, the cabinet has lots of water damage and the big transformer at
the bottom of the cab is covered with rust. The cap looks OK but since I
haven't looked at the output of the supplies with a scope I can't rule it
out as a problem yet.

A 4 amp 250v slow-blow fuse was missing for the 22v line. We replaced
that and disconnected the game PCB so we could determine whether the PS
is good or not.

The bipolar 22 and unreg 10.3v lines are good voltage wise. Dunno about
ripple though.

The big question is we tried to measure the 5v line and we saw the same
output as the 10.3v line. I had the DMM leads on +sense and ground. I
even shorted out the sense resistors and that had no effect.

Now some questions for the panel...

Does this mean what I think it might for the logic PCB (i.e. toasted
beyond repair) or did I just forget something stupid?

I checked out all the semis except the LM305 and they tested good on my
Radio Shack DMM (I should still recheck CR4 though). The caps looked &
checked OK. The resistors were OK as well. No post-traumatic immolation
disorders here or on the logic PCB as well. I am going to sub the LM305
with one from another AR2 and maybe CR4. Is this a common failure?

Thanks in advance!

Virtu-Al

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Received on Wed Oct 14 23:16:56 1998